Nowadays machines are known for providing corrugated sheet-like elements, of various materials, to be used, for example, for packaging, or for thermal or acoustic insulation.
Conventional machines usually comprise two chain conveyors, or formers, which move a plurality of transverse vanes, or bars, also known as rods, along a closed path.
In the known art, as disclosed in EP1620253B1 by the same Applicant, such rods are brought to the working position by a dedicated mechanism.
Specifically, the transverse vanes of each conveyor make up a kind of comb. The vanes of a conveyor face, in the work area (or formation area) of the corrugated sheet-like element, toward the vanes of the other conveyor, interleaving with them. The sheet-like element is thus pushed by the vanes of the two conveyors which, by mutually interleaving, press the sheet-like element thus creating the typical “wave” deformation of the element.
Such conventional machines also comprise means for bonding the corrugated sheet-like element thus obtained, to one or more other flat sheet-like elements, at the peaks of the formed corrugations, in order to provide a compound structure.
The conventional machines described above suffer the drawback of being very complex and expensive in that they use rods which are inserted to form the corrugation and are then extracted from the corrugation after the heat-sealing.
Other machines also exist which do not use rods but which instead form corrugations using only elastic materials such as for example expanded polyethylene.
Another category of conventional machines are the rotary machines that are typically used in the formation of cardboard. All manufacturers of such machines make use of roller formers provided with teeth, very similar to rounded gearwheels, which do not enable the formation of acute and right angles and which favor the formation of a sinusoidal corrugation.
Such conventional machines are also not devoid of drawbacks. In particular, such machines suffer limitations relating to the shape structure that they are capable of imparting to the corrugations of the corrugated sheet-like element. Specifically, such machines make it possible to provide substantially sinusoidal corrugations, in which the pitch-to-height ratio of the corrugation is substantially equal to 2.
Another drawback is constituted by the fact that the height of the corrugation is directly linked to the diameter of the roller formers. The impossibility of making rollers of excessively large diameter effectively limits the thickness of the cardboard to a height of 5 mm. If greater heights are needed, use is made in fact of the superimposition of multiple layers of cardboard.
However, theoretically, the ideal solution in order to optimize consumption of the material of which the corrugated sheet-like element is made and at the same time optimize the strength of the aforementioned compound structure provides a corrugation profile which is approximately triangular. In particular, the more acute the angle at the vertex of the triangle, the greater is the number of corrugations that can be provided for the same length, and therefore the greater is the resistance to compression of the compound structure.
The aim of the present disclosure is to provide a machine for providing corrugated sheet-like elements which solves the above-mentioned drawbacks and overcomes the limitations of the known art.